Method and apparatus for forming a reflector support on an incandescent lamp



Oct. 15, 1940. R. WA WENGEL 2,218,254 METHOD AND APPARATUS FOR FORMING A REFLECTOR SUPPORT 0:1 AN INGANDESCENT LAMP Filed Sept. l5, 1939 @Vm/MMM INV NT Patented Oct. l5, 1940 PATET ori-ica METHOD AND APPARATUS FOR FORMING4 A REFLECTOR SUPPORT 0N AN INCANDES- CENT Raymond W. Wengel, Rochester, N. Y., asslgnor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application September 13, 1939, Serial No. 294,726

Claims.

The present invention relates to a method and apparatus for forming a reector support and a reector on the glassenvelope or bulb of a gaslled incandescent lamp and more particularly -to the use of the lamp filament for .heating the glass to a plastic state and for heating the gases to expand a portion of the glass envelope.

` The provision of. reflector supports or reflectors on incandescent lamps has already been accomplished but for the most part the formation of the reector support is accomplished at the time that the glass bulb is made and is accomplished by various procedures known to the glass-making or glass-blowing art.

'Ihe primary object of the present invention is the provision of a method and apparatus whereby a reflector support and a reflector may be respectively formed in and coated on the lamp after it has been manufactured.

A further object of the invention is a method and apparatus for utilizing heat from the lamp filament to heat the glass and to expand the gases -in the lamp to deform a portion of the glass bulb.

Another object of the invention is the method and apparatus whereby the deformation of the glass bulb may be accomplished in such a manner that the reflecting surface coated thereon" will reect the image of the filament without interference with the lamp filament.

Still another object of the invention is to control the deformation of the glass bulb by a mold having a mold lcavity with a polished surface.

A still further object of the invention is the use of a radiating means for re-radiating the heat from the lamp filament so as to heat only predetermined portions of the glass bulb.

Other and further objectsof the invention willl be suggested to those skilled in the art by the disclosure which follows.

Ihe above and other objects of the invention are accomplished by a method for forming a reflector on the glass envelope of a gas-filled incandescent lamp having a filament by passing an electric current through the filament, heating the glass envelope by theI heat from said filament, heating the gases in said glass envelope also by the heat from sald filament to expand said gases anddeform a portion of said glass envelope, and then covering the deformed portion of said glass envelope with a refiecting layer. The apparatus for forming the reflecting support on said glass envelope comprises a support for the lamp, a mold provided with a cavity having a polished surface and supported adjacent the envelope of the lamp, adjustlnglmeans for relatively moving said support and lamp with respect to said mold, and a radiating member located adjacent said glass envelope for re-radiating the heat from said filament to heat said envelope and provided with openings arranged for observation of the filament image reflected from the polished surface of the mold cavity.

Reference is hereby made to the accompanying drawing wherein similar reference characters designate similar elements and wherein:

:Fig 1 is a side elevation in partial section of the apparatus for forming a reflector support on the glass bulb of an incandescentlamp according to the invention.

Fig. 2 is a plan view of such apparatus which is shown inFig. 1.

IFig. 3 is aside elevation of an incandescent lamp which has been provided with a reflector according to the method and apparatus of the invention.

Fig. 4 is a wiring diagram of a modified circuit which may be used for energizing the lamp lamen't.

In the illustrated embodiment of the invention, a frame member I0 is provided with a guideway II. yentional form such as used in motion picture projectors and comprises anelongated tubular glass envelope I3 fastened to a metal base I4. The filament I5 is supported by the stem I6 and wire Il within said glass envelope I3 and is connected in a well known manner at one end to the metal .base I4 and at the other lend to the contact I8. 'I'he metal base I6 flts into asocket I9 from which extends a. tube 20 and a cable 2l.

The arrangements for connecting the lamp flla- A ment to a supply of energy may be made in sev- .eral ways, for example, one leg 22 of cable 2| is connected directly to one side of an energy supply. while the other leg 23 of cable 2| may include a rheostat 2t.. Said rheostat 24 may comprise a contact arm 25 and a circular resistance element 26. When the contact varm 25'is in the position 'I'he incandescent lamp I 2 is of con-.

shown all of the resistance of rheostat 2li is in the lamp filament circuit'and only a lovv filament current may be supplied. On the other' hand, when contact arm 25 is in its 4other extreme position, little if any, of the resistance element willl ber 3I to which the mold 21 is fastened by bolts 32. An adjusting means for relatively moving the lamp I2 with respect to the mold 21 may include several individual adjustments as shown or may comprise a universal movement type of support. The provision of vertical, transverse and longitudinal adjustments permits very accurate relative location of a lamp filament I5 with respect to the polished surface of the mold cavity 28 and is, therefore, preferred, although the adjusting means can be considerably simplied as by using a ball and socket support which will not be susceptible of extremely accurate adjustment.

The adjusting means shown comprises a slide 33 movable within gi'iidevvay` II by means of a screw 34 having a handle 35, having a head 36 rotatably engaging a plate 31 bolted to slide 33 and threaded through a plate 38 which is bolted to frame member I0.

A hollow standard -39 has a slide 40 movable in a transverse guideway 4I provided in slide 33. Transverse movement of slide 40 is obtained by a screw 42 having a handle 43, threaded through a plate 43 bolted to slide 33, and having a head 45 engaging but rotatable in a plate 44 which is bolted to the end of slide 40. Rotation of handle 43 and screw 42 will accomplish transverse movement of the slide 40 and standard 39 with respect to frame member I0.

Vertical adjustment of the lamp may be accomplished by a pinion gear 41 fastened to a shaft 48 which is journaled in lugs 49 of standard 38 and which carries a notched handle 50. The wall of hollow standard 39 is provided with an opening 5| through which pinion gear 41 extends into engagement with a rack portion 52 of a post 53. Obviously, rotation of handle 58 will raise or lower said post 53.

A clamp member 54 fits over the end of post 53, is provided with a slot 55, and -has a bolt 53 for tightening one slottedl end of clamp member 54 upon the post 53. In a similar manner the other end of clamp member 54 fits over tube 20, is provided with a slot 51 and carries a bolt 58 which may be tightened to fasten the other end of clamp member 54 to said tube 20.

In order to control or localize the heating of the glass envelope I3, a radiating member is located adjacent the glass envelope for re-radiating Vthe heat from said filament selectively to heat the glass envelope I3. Such a radiating member may comprise a metal tube 59 fitted over the glass envelope I3 and provided with an opening 60 opposite the mold 21 and also provided with an opening 6I on the other'side of the tube 59 for a purpose which will be later described. y Although the radiating member as shown is in contact with the glass envelope I3, it is to be understood that such radiating member may be spaced from the glass envelope I3 and may be supported independently of the lamp I2.

In order to linsure that the glass envelope I3 is not deformed at other points than .those desired to be deformeda cooling means is provided. Any cooling means that will accomplish selective cooling of the glass envelope is suitable. For purposes of illustration the cooling means may comprise a fan 32 attached to the frame member I and connected to blow air through semi-flexible tubes 63 and 64. The tube 63 directs an air blast onto that portion of glass envelope I3 which is opposite the mold 21, while the tube 64 directs an air blast onto that portion of the glass envelope I3 which is adjacent the metal base I4. The circulation of the air at this point may be further improved by the provision of a shield 55 fastened to socket I9. I

For best lighting efficiency from a lamp carrying a reflector, it is necessary that the reflected image of the filament shall not interfere with or be shadowed by the lamp filament. The present method and apparatus are extremely well suited to the provision of the reflector so that such in terference or decrease in efficiency does not occur. Since the mold cavity 28 has a polished surface, the reflection of the filament image from said polished surface is the same as will be obtained from the reflecting layer which will be later placed upon Ithe deformationin the glass envelope I3. Consequently, a low filament current is first supplied to the lamp and the filament image reflected from the polished surface of .mold cavity 28 is observed. In. order to facilitate such observation, the radiating member or metal tube 59 is provided with the opening 6I and a refiecting means is movable into the path of the light beam. Such reflecting means may comprise an inclined support 66 pivotally mounted to swing about a vertical axis by abracket 61 attached to the support and pivoted by a pin 68 to a lug 89 on one of legs 3D. A mirror 10 is fastened by clips 1I to one side of support 55. This reflecting member may be swung into the position shown by the dot-dash lines of Fig. 1 for reflecting the direct image and refiected image of the filament to a convenient place at one side of the apparatus or the reflecting means may be swung into an inoperative position as shown by the full lines inr Figs. 1 and 2l so that the semi-flexible tube 83 may be placed adjacent the opening I of tube 59 for cooling of the portion of the glass envelope I3 which is adjacent said opening 6I.

Since it is more desirable to adjust the lamp I2 and its filament I5 with respect to the polished surface of the mold cavity 28 while a low filament current is passing through the lamp, it is preferable to provide a current control means or rheostat in the filament circuit but such current control or current reducing means is not absolutely necessary. The current control means may be simplified in several ways, one'of which is indicated in Fig. 4. One side of the filament I5 of lamp I2 is connected by a wire 22 to the supply of energy, while the other side of filament I5 is connected by the wire 23 either directly to the other side of the energy supply or through a fixed resistance 12 to the other side of said energy supply. A single-pole double-throw switch 13 in the position shown connects the filament directly to the current supply, whereas, when switch 13 is moved to its other position, the fixed resistance 12 is connected in the filament circuit and the filament is maintained at a lesser brilliance for easier adjustment of the lamp with respect to the mold 21.

While one form of the apparatus for performing the .method of the invention has been disclosed, it shall be understood that lthe method may also be accomplished with other forms of apparatus.

The procedure for performing the invention will now be reviewed. Basically, the method of the invention is accomplished by merely passing through the lamp a lament current sufficiently high to heat the glass envelope to plasticity and to expand the gases in the lampfor deformation of a portion of the -glass envelope. 'I'he deformation of the glass bulb or envelope may be irregular unless mechanical control is exerted over the molten glass. Consequently, the mold 21 is preferably employed and the concave cavity 28 in the mold is formed so that the deformed portion of the glass envelope is a curved or spherical surface having its center at the lamp filament.

It has been found that the heat from the filament may be more efficiently utilized afterA a radiating means is placed adjacent the glass envelope to receive the intense radiant energy from the filament and re-radiate it to the glass bulb.

Also in this manner selected portions of the glass rately controlled by the use of the forming ele-v l ment.

In other words, the polished surface of the mold for the deformed portion of the bulb acts as a reflector during adjustment of the incandescent lamp with respect to the mold. Preferably, a low filament current is first supplied to the filament I5 either by use of a rheostat as shown in Fig. 1 or a. switch and fixed resistance as indicated in Fig.r4. The operator, subjected to little or no blinding from the light, is able to observe the filament and its image as reflected from the polished surface of cavity 28 and to adjust any or all of the handles 35, B3 or 50 until the reflected'image of the filament does not overlap or coincide with the actual filament. In the case of spaced filaments as commonly used, the reflected images of the filament sections come between such sections so that there is apparently a solid mass of incandescent filament.

After such adjusting operations have been performed the mirror 10 is moved out of position from beneath the lamp I2 and mold 21, the semiflexible tubes 63 and 64 for the air blast are arranged as desired and the current control means is moved so that a high filament current passes through said filament I5. As above explained, the heat from the filament is re-radlated from the metal tube 59 and portions of the glass envelope I3, particularly around the opening 60 and tube 59, are heated to a plastic condition, the air blast from tubes 63 and 64 maintaining the neck of envelope I3 and the portion adjacent opening 6I in a relatively cool condition.

Finally, the portions of the glass envelope and the gases in the lamp I2 attain a temperature such that the gases expand to deform the glass envelope I3 and to force it onto the cavity 28 of mold 21. bulged portion of the glass envelope conforms precisely to the polished surface of mold cavity 28 and a reiiector support is provided directly in the glass envelope I3 of the lamp I2.

The reiiecting layer on the deformed portion of the glass envelope may be provided in any of the several ways now known for forming mirrors or reflecting surfaces on glass. For instance, aluminum or other metal may be sprayed onto the glass envelope, preferably while its deformed portion is still hot. 'I'he aluminum may be sprayed by the Schoop process or Silver may bev deposited on such deformed portion of the glass bulb by means of the Brasher process. Furthermore, if desired, the reflecting layer may then be covered by a suitable protective coating so that.

In this manner the deformed or the reflecting surface will not become scratched or marred.

One great advantage of providing a reflecting portion directly on an incandescent lamp is that each time that a lamp is changed a new mirror is brought into use. Thus deterioration of the lamp mirror is limited' to the life of a single lamp and does not continue throughout the life of the apparatus, such as a motion picture projector and during the use of several lamps.

Since many variations of the present invention are possible, the scope of the invention is to be determined by the claims which follow.

Having now particularly described my invention what I desire to secure by Letters Patent of the United States and what I claim is:

1. A method for forming a reflector on the glass envelope of a gas-filled incandescent lamp having a filament, which comprises passing an electriccurrent through said filament, heating said glass envelope by the heat from said filament, heating the gases in said glass envelope also bythe heat from said filament to expand said gases and deform a portion of said glass envelope, and covering the deformed portion of said glass envelope with a reflecting layer.

2. A method for forming a refiector on the glass envelope of a gas-filled incandescent lamp having a filament, which comprises passing an electric current through said filament, heating a portion of said glass envelope to a plastic condition by the heat from said filament, heating the gases in said glass envelope also by the heat from said filament to expand said gases and said heated portion' of said glass envelope, and covering the Aexpanded portion of said glass envelope with a, reflecting layer having a reiiecting surface facing said filament.

3. A method for forming a reflector'on the glass envelope of a gas-filled incandescent lamp having a filament, which comprises passing an electric current through said filament, heating a portion of said glass envelope to a plastic condition by the heat from said filament, cooling a portion of said envelope to prevent deformation thereof, heating the gases in said glass envelope also by the heat from said filament to expand said gases and said heated portion of said glass envelope, and covering the expanded portion of said glass envelope with a reflecting layer having a reecting surface facing said filament.

4. A method for forming a reflector on the glass envelope ofv a gas-filled incandescent lamp having a filament, which comprises passing an electric current through said filament, selectively reradiating the heat from said filament to heat a portion Aof said glass envelope to a plastic condition, heating the gases in said envelope by the heat from said filament to expand said gases and the heated portion 'of said glass envelope, and Ycoating a reflecting layer onto the expanded portion of said glass envelope;

5. A method for forming a reflector on the glass envelope of a gas-filled incandescent lamp 6. n method for forming a reflector on the glass envelope of a gas-filled incandescent lamp 'having a filament, which comprises passing an electric current through said filament, selectively reradiating `the heat from said filament to heat a portion of said glass envelope to a plastic condition, heating the'gases in said envelope by the heat from said filament to expand said gases and said heated portion of said glass envelope, mechanically controlling the expansion of said heated portion of said glass envelope to form a spherical surface with its center of curvature at said filament, and coating said spherical surface with a refiecting layer having a refiecting surface facing said filament.

7. A method for forming a reiiector on the glass envelope of a gas-filled incandescent lamp having a filament, which comprises passing an electric current through said filament, selectively re-radiating the heat from said filament to heat a portion of said glass envelope to a plastic condition, cooling a portion of said envelope to prevent deformation thereof, heating the gases in said envelope by the heat from said filament to itli` expand said gases and said heated portion of said glass envelope, mechanically controlling the expansion of said heated portion of said glass env elope, and coating a refiecting layer onto the expanded portion of said glass envelope.

8. A method for forming a reflector support on the glass envelope of a gas-filled incandescent lamp having a filament, which comprises passing a relatively low current through said filament, refiecting an image of said filament from a surface complementary to that desired for the relector support, passing a relatively high current through said filament, heating said glass envelope by the heat from the high filament current, and

. heating the gases in said glass envelope also by and supported adjacent the envelope of said lamp, adjusting means for relatively moving said support and lamp with respect to said mold, and a radiating member located adjacent said glass envelope for re-radiating the heat from said filament to heat said envelope and provided with openings arranged for observation of the filament image reflected from the polished surface of the mold cavity.

10. An apparatus forforming a reflector support on the glass bulb of an incandescent lamp having a filament, comprising a frame, a support 4member for said lamp, means for connecting the filament thereof to a supply of. energy, a mold member provided with a cavity having a polished surface and supported adjacent'the glass bulb of said lamp, and adjusting means between said frame and one of said members and for moving said lamp relatively of said mold member whereby the filament image reected from the polished surface of the mold cavity can be adjusted with y respect to the lamp filament.

11-. Anapparatus for forming a reflectorsupport on-the glass envelope of an incandescent lamp havingv a filament, comprising asupport for said lamp, means for connecting the filament of said lamp to a supply of energy, a mold.l provided with a cavity and supported adjacent the envelope of said lamp, and a radiating member located adjacent said lamp for selectively reradiating the heat from said filament to heat said envelope adjacent said mold whereby the gases in said lamp expand to bulge a portion of said envelope into the cavity of said mold.

12. An apparatus for forming'a refiector support on the glass envelope of an incandescent lamp having a filament, comprising a support for said lamp, means for connecting the filament of said lamp to a supply of energy, a mold provided with a cavity and supported adjacent the envelope of said lamp, a radiating member located adjacent said lamp for reradiating the heat from said filament to heat said envelope adjacent said mold, and cooling means arranged to cool portions of said glass envelope and prevent rtheir deformation by the gases under pressure in said envelope.

' 13. An apparatus for forming a reflector support on the glassL envelope of an incandescent lamp having a filament, comprising a support for said lamp, a lamp circuit including the lamp filament and a current control for a low filament current and a high filament current, a mold provided with a cavity having a polished surface and supported adjacent the envelope of said lamp, adjusting means for relatively moving said support and lamp with respect to said mold during a low filament current and for adjusting the filament image refiected from the mold cavity with respect to the lamp filament,`and a radiating member located ,adjacent said glass envelope for reradiating the heat from said filament when carrying a high filament current to heat said envelope whereby the gases in said lamp expand to bulge a heated portion of said envelope into the cavity of said mold.

14. An apparatus forforming a refiector support on the glass envelope of an incandescent lamp having a filament, comprising a support for said lamp, means for connecting the filament of said lamp to a supply of energy, a mold provided with a cavity and supported adjacent the envelope of said lamp, a radiating member located adjacent said lamp for selectively reradiating the heat from said filament to heat selected portions of said envelope, and a cooling means circulating air over other portions of said envelope which are not to be deformed.

15. An apparatus for forming a reiiector support on the glass envelope of an lincandescent lamp having a filament, comprising a support for said lamp, means for connecting the filament of said lamp to asupply of energy, a, mold provided with a cavity and supported adjacent the envelope of said lamp, a radiating member located adjacent said lamp for selectively reradiating the heat from said filament to heat a selected portion of said envelope, an air impelling means, and semi-flexible conduits for directing air from said air `impelling means onto portions of said envelope not tobe deformed.

RAYMOND W. W'ENGEL. 

